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| #540838 (Received by flhurricane at: 10:35 PM 06.Sep.2012) TCDAT3 HURRICANE MICHAEL DISCUSSION NUMBER 16 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132012 1100 PM AST THU SEP 06 2012 THE CONVECTIVE COLD TOPS HAVE BECOME A LITTLE LESS SYMMETRIC AROUND THE EYE DURING THE PAST FEW HOURS...AND RECENT MICROWAVE DATA INDICATE THAT MICHAEL POSSESSES A THIN BUT CLOSED EYEWALL. DVORAK CURRENT INTENSITY ESTIMATES ARE NOW 90 KT FROM TAFB AND 77 KT FROM SAB...AND THE LATEST UW-CIMSS ADT ESTIMATE IS T4.9/5.2. THE INTENSITY IS LOWERED A BIT TO 90 KT BASED ON A BLEND OF THESE DATA. MICHAEL HAS FOUND ITSELF STUCK BETWEEN TWO MID-/UPPER-LEVEL LOWS... EACH ROUGHLY EQUIDISTANT TO THE NORTHEAST AND SOUTHWEST OF THE HURRICANE. THE COMPETING FLOWS AROUND THE LOWS HAVE CAUSED MICHAEL TO SLOW DOWN...AND THE INITIAL MOTION IS ESTIMATED TO BE 025/4 KT. THE STEERING CURRENTS OVER THE CENTRAL ATLANTIC ARE EXPECTED TO REMAIN WEAK...AND MICHAEL IS FORECAST TO CREEP NORTHWARD TO NORTHWESTWARD DURING THE NEXT 3 TO 4 DAYS. THE GLOBAL MODELS THEN AGREE THAT THE CYCLONE WILL ACCELERATE NORTHWARD BY DAY 5 AHEAD OF AN APPROACHING MID-LATITUDE TROUGH...AND WITHIN THE SOUTHERLY FLOW AHEAD OF HURRICANE LESLIE. THE UPDATED TRACK FORECAST IS VERY SIMILAR TO THE 21Z FORECAST DURING THE FIRST 72 HOURS...AND IS THEN A LITTLE TO THE WEST AND FASTER BY DAY 5 TO BE CLOSER TO THE MODEL CONSENSUS TVCA. ACCORDING TO THE SHIPS DIAGNOSTICS...MICHAEL SHOULD BE IN A RELATIVELY SHEAR-FREE ENVIRONMENT FOR THE NEXT 72 HOURS. HOWEVER...THE UPPER-LEVEL PATTERN OVER THE CENTRAL ATLANTIC IS COMPLEX...AND IT IS POSSIBLE THAT THE OUTFLOW FROM LESLIE COULD AFFECT MICHAEL SOONER THAN SHOWN BY THE SHIPS GUIDANCE. THE NHC INTENSITY FORECAST CONTINUES TO SHOW ONLY GRADUAL WEAKENING DURING THE NEXT 4 DAYS...WHICH IS SUPPORTED BY MOST OF THE GUIDANCE. FASTER WEAKENING IS EXPECTED BY DAY 5 ONCE THE DEEP-LAYER SHEAR BECOMES DECIDEDLY STRONGER...AND MICHAEL COULD BE CLOSE TO BEING EXTRATROPICAL BY THAT TIME AS WELL. FORECAST POSITIONS AND MAX WINDS INIT 07/0300Z 30.8N 40.8W 90 KT 105 MPH 12H 07/1200Z 31.2N 40.9W 85 KT 100 MPH 24H 08/0000Z 31.7N 41.5W 80 KT 90 MPH 36H 08/1200Z 32.3N 42.0W 80 KT 90 MPH 48H 09/0000Z 33.0N 42.5W 75 KT 85 MPH 72H 10/0000Z 34.5N 44.0W 70 KT 80 MPH 96H 11/0000Z 36.5N 46.0W 65 KT 75 MPH 120H 12/0000Z 43.0N 47.0W 50 KT 60 MPH $$ FORECASTER BERG |
